False Positive - OPK (digital)

[Claire10]

I took a clearblue digital opk and got a positive (smiley face) but when I took the stick out there was only one line and a blue streaky smudge across the place where the other line should appear. I took another one 30 min later and it was negative but as it was only 30 min later I'm not sure if the quality of the sample was a problem even though I didn't consume any water.

Is it possible to get a false positive OPK if too much urine is applied? Any ideas?

[pokeyAC]

I have often pulled out the stick and seen a streaky smear of blue.  This happened even when I dipped the stick into a cup instead of actually POAS.  The directions tell you not to look at the stick.  It often doesn't look like a regular 2-line test would.  They also tell you to wait 4 hours without urinating before you take a test so that could explain the negative.  If you google false positive on these tests you will finds lots of info that isn't conclusive.  I didn't feel like it answered anything for me.  I have wondered if I was getting false positives with these too.  I would suggest looking at your other fertility signs.  If you have 2 other signs that say fertile, it was probably a real positive.  For example, do you have EWCM and is your cervix high and soft?  Then it was probably a real positive.  Are you concerned because it seems earlier than you normally get a positive?  Have you been charting or only using OPK's?  Good luck!